Rotating thermal convection experiments in a hemispherical shell with heterogeneous boundary heat flux: Implications for the Earth's core

被引:26
|
作者
Sumita, I [1 ]
Olson, P
机构
[1] Kanazawa Univ, Fac Sci, Dept Earth Sci, Kanazawa, Ishikawa 9201192, Japan
[2] Johns Hopkins Univ, Dept Earth & Planetary Sci, Baltimore, MD 21218 USA
关键词
core-mantle boundary; heat flux heterogeneity; outer core; inner core; thermal convection experiment; rotating spherical shell;
D O I
10.1029/2001JB000548
中图分类号
P3 [地球物理学]; P59 [地球化学];
学科分类号
0708 ; 070902 ;
摘要
[1] We report the results of thermal convection experiments in a rapidly rotating hemispherical shell with a heterogeneous heat flux at the outer boundary to model the effect of a thermally heterogeneous core-mantle boundary on the convection in the Earth's outer core. A parameter study is made by varying the heat flux, size, and location of an anomalously heated patch for a range of Rayleigh numbers at similar to10(8) and a fixed Ekman number 4.7 x 10(-6). Experiments show that fully developed, boundary-driven convection occurs when the radial convective heat transfer from the heater exceeds that of the surrounding boundary region. The flow consists of a large-scale cyclonic circulation originating from the heater and includes a radially extending spiralling front with a jet. The front is stationary when the sectorial high heat flux region is imposed at low latitudes but becomes unstable when it is imposed at high latitudes. The ratio of applied heat which is partitioned to radial and lateral heat transfer becomes fixed in this regime. Measurements also indicate that there is a close correlation between the flow direction and the statistics of temperature fluctuations. Applied to the Earth, the experiments suggest that there are two scales of flows in the core: fine-scaled jets and slower, large-scale flows. The large-scale hemispherical structure of the core can be interpreted in terms of the boundary-driven flow driven by the high heat flow region beneath east Asia.
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页数:18
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